APPETITE OF SWINE 
389 
In these 71 days, . comparing* each lot to what it did in the 
first preliminary 90 days, we find that: 
Lot I gained 84.24 per cent as much. 
Lot II gained 94.02 per cent as much. 
Lot III gained 96.97 per cent as much. 
Lot IV gained 94.13 per cent as much. 
Lot V gained 97.23 per cent as much. 
It ■ is thus readily seen that the proportionate gain of the 
‘‘salt ad libitum lot” was greater than any of the other lots. 
It is well to note that the “36 grams lot” seemed to do better 
than either “18” or “72 grams”, in other words, an optimum 
was more closely approximated with an allowance of 36 grams or 
4.5 grams per head daily ; less salt than this was not so good, nor 
was more. The striking feature of this is that the free-choice 
group ate on the average just 3.45 grams daily, which would 
•indicate that this was more nearly optimum than the 4.5 gram 
allowance of Lot III which is excelled. 
Now, let us look to the feed requirement for a hundred pounds 
of gain in these 71 days as compared with the check preliminary 
period of 90 days as before.: 
Lot I required 101.88 per cent as much feed. 
Lot II required 94.29 per cent as much feed. 
Lot III required 91.56 per cent as much feed. 
Lot IV required 89.92 per cent as much feed. 
Lot V required 89.36 per cent as much feed. 
The requirement for a hundred pounds of gain was compara- 
tively less, therefore, in the “salt ad libitum” group (Lot V) 
than where the salt was omitted (Lot I) or mixed with the feeds 
(Lots II, III, and IV). It is quite evident that the addition of 
salt in varying amounts results, in every instance, in a cheap- 
ening of the gain; the feed required for a hundred pounds of 
gain was lessened. It is quite evident that the pigs which re- 
ceived salt according to their appetite made relatively the most 
economical gains of any group. The free-choice group compared 
to the “no salt group” in the 71 day salt feeding period re- 
quired only 89.36 in contrast with 101.88 per cent as much feed 
as in the preliminary. 
Evidently the salt requirement of these pigs was not constant 
throughout the experiment. This is manifested in the exhibi- 
tion of their appetite, clearly shown in the data. The incon- 
stant demand for salt makes it very difficult to apnortion the 
